Melt launder

ABSTRACT

The invention relates to a melt launder ( 1, 9, 10 ) comprising a bottom and edges, said melt launder being particularly meant to be used for tapping a molten phase, such as slag, from a smelting furnace, which melt launder is manufactured of copper or copper alloy and provided with cooling channels ( 8 ), so that at the bottom ( 2 ) of the melt launder ( 1, 9, 10 ), there is arranged at least one groove ( 3 ).

[0001] The present invention relates to a melt launder defined in thepreamble of claim 1, to be used particularly for tapping a molten phase,such as slag, from a smelting furnace. The melt launder is made ofcopper or copper alloy and is provided with cooling piping at the edges.

[0002] For tapping a molten phase such as slag from a smelting furnace,there are often used copper launders, either water-cooled or uncooledlaunders. The temperature of the melt is very high when it is tapped outof the furnace. When tapping melt from the furnace, an amount ofsomewhat solidified slag also enters the launder, and this solidifiedslag protects the launder against damages caused by the heat, such asheat expansion. However, at the beginning of the tapping step, thelaunder surface facing the molten slag is often heated up to a hightemperature before the slag is solidified, which may cause damages inthe launder. There are often used melt launders provided with coolingpiping that which protects the launder against damages.

[0003] From the publication JP-A-7305966, there is known the method ofdrilling water channels in the launder in order to preventtransformation damages. The water channels are arranged in the launderso that they protect the whole launder housing. Also from thepublication FI 990513 there is known a launder that is provided withcooling piping at the edges.

[0004] However, generally it is not desirable to increase the coolingfor repairing launder damages, because in copper smelting, in connectionwith tapping melt, such as slag, this may result in that also moltencopper is tapped, and as a result blister copper enters the coolingpiping and causes an explosion.

[0005] The object of the invention is to achieve a melt launder wherebythe prior art drawbacks are avoided. According to the present invention,there is developed a melt launder where the bottom that is in contactwith the melt is provided with grooves, and the grooves are filled withfire-resistant material that is in the course of time naturally replacedwith slag. Said material protects the launder against possibletransformation damages at the beginning of the tapping step. Above themolten surface, the melt launder edges are provided with cooling waterchannels that are arranged so that water does not in any case get intocontact with the melt.

[0006] The invention is characterized by what is set forth in thecharacterizing part of claim 1. Other preferred embodiments of theinvention are characterized by what is set forth in the other claims.

[0007] The melt launder according to the invention advantageouslyprevents melt launder damages created in connection with the tapping ofa molten phase, such as slag, particularly at the beginning of thetapping step. The grooves provided according to the invention at thelaunder bottom are filled with fire-resistant material that endures hightemperatures. The fire-resistant mass located on the launder bottomadvantageously protects the launder bottom against wearing. By using themelt launder according to the invention, there is achieved a longerworking life for the launder, which also means savings in the expenses.Another advantage of the invention is that when the fire-resistant massis detached, it is autogenously replaced by slag.

[0008] At the bottom of the melt launder according to the invention,there is arranged a required number of grooves proceeding in thelengthwise direction thereof, said grooves ending at both launder endsin a transversal groove. Said transversal groove extends from onelaunder edge to the other. The depth of the lengthwise groove mayadvantageously vary within the range of 5-25 millimeters, and its widthmay advantageously vary within the range of 5-25 millimeters, dependingon the size of the melt launder. The distance between the lengthwisegrooves may advantageously vary between 5-25 millimeters. The lengthwisegroove must be placed at a given distance from the cooling water pipingslocated at the launder edges. Said distance is advantageously at least30 millimeters.

[0009] The invention is described in more detail below with referencethe appended drawings.

[0010]FIG. 1 Cross-sectional illustration of a melt launder according tothe invention

[0011]FIG. 2 Cross-sectional illustration of a melt launder according toanother embodiment of to the invention

[0012]FIG. 3 Cross-section illustration of a melt launder according to apreferred embodiment of the invention

[0013] In FIG. 1, there is seen a melt launder 1 according to apreferred embodiment of the invention, made of bent copper plate, and onthe bottom 2 of said launder there are made grooves 3. The figure is across-sectional illustration showing the middle of the melt launder. Thenumber of the grooves 3 made at the bottom of the copper plate can beany desired number, at least one. At the launder bottom, the grooves areplaced in an uncooled area, i.e. between the lowest cooling channels.The grooves can be made either in connection with casting, or by makingthem in the ready-made launder. According to this preferred embodiment,the grooves provided nearest to the edges cannot be located nearer than30 mm from the edge of the cooling channel 8. In shape, the groove canrepresent any possible form. According to the present embodiment, thegrooves are 10-20 mm deep and 10 mm wide, at a distance of 20 mm fromeach other. Said measures may vary depending on the size of the meltlaunder. The melt launder comprises a required number of grooves in thelengthwise direction of the launder, in addition to which both ends ofthe launder are provided with transversal grooves that are not seen inthe cross-sectional illustration. Said transversal grooves are made atboth ends of the launder, and they extend from one launder edge to theother, so that a longer working age is achieved for the launder. At bothends of the launder, the lengthwise grooves end at a transversal groove.The grooves 3 as well as the transversal grooves are filled withfire-resistant mass that is partly worn away when tapping molten slag 5and is autogenously replaced by solidified slag 6. At the edges 7 of thelaunder, there are arranged cooling channels 8; they are placed in anarea that is not left under the melt when the melt 5 is being tapped.The cooling channels 8 are manufactured either in connection with slipcasting or by drilling lengthwise holes at the edges 7 of a bent copperbillet. In the cooling channels, there flows water that preventsexcessive heating. A required number of channels is provided.

[0014]FIG. 2 shows the end of a melt launder 9 according to anotherpreferred embodiment of the invention, seen in a cross-sectionalillustration. It is manufactured by compactly interconnecting twostraight plates made of copper or copper alloy, so that the edges 7 andthe bottom 2 are made of said plates. Now that area at the bottom 2 thatgets into contact with the melt 5 is provided with grooves 3, which arethen filled with fire-resistant mass. The melt launder is provided witha necessary amount of grooves 3, proceeding in the lengthwise directionthereof, as well as with two transversal grooves 12 arranged at bothends of the launder. The transversal grooves are made at both ends ofthe launder, and they extend from one launder edge 7 to the other, sothat a longer working life is achieved for the launder. At both ends ofthe launder, the lengthwise grooves of the launder end in a transversalgroove. Partly the grooves are worn away when tapping slag or whencleaning the launder, and they are autogenously replaced by solidifiedslag 6. The grooves can be made either in connection with casting or byworking them in a ready-made launder. The cooling channels 8 are placedat the edges 7 in the lengthwise direction of the melt launder, so thatthey are not left underneath the melt surface.

[0015]FIG. 3 illustrates a preferred embodiment of the invention. Thebottom 11 and the edges 7 of the melt launder 10 are manufactured ofseparate parts. The bottom 11 is bent of metal and provided with grooves3. The edges 7 made of straight plates are connected to the bottom 11,so that a sufficient compactness and heat transfer are achieved. Themelt launder is provided with a required number of grooves in thelengthwise direction thereof, in addition to which both ends of thelaunder are provided with transversal grooves that are not shown in thecross-sectional illustration. The transversal grooves are made at bothends of the launder, and they extend from one edge of the launder to theother, so that a longer working life for the launder is achieved. Atboth ends of the launder, the lengthwise grooves end in a transversalgroove. The grooves 3 as well as the transversal grooves are filled witha fire-resistant mass that is partly worn away when tapping molten slag5 and is autogenously replaced by solidified slag 6. The edges 7 areprovided with cooling channels 8, located above the melt surface 5.

[0016] For a man skilled in the art, it is apparent that the variouspreferred embodiments of the invention are not restricted to thosedescribed above, but may vary within the scope of the appended claims.

1. A melt launder comprising a bottom and edges, said melt launder being particularly meant to be used for tapping a molten phase, such as slag, from a smelting furnace, said melt launder being manufactured of copper or copper alloy and provided with cooling channels, the bottom of the melt launder having at least one groove and the cooling channels being situated in the lengthwise direction of the melt launder so that they remain above the surface of the melt.
 2. A melt launder according to claim 1, wherein the bottom, has at least one lengthwise groove and at least one transversal groove.
 3. A melt launder according to claim 1 wherein, a fire-resistant mass is situated in the grooves.
 4. A melt launder according to claim 1, wherein the fire-resistant mass is capable of being autogenously replaced by solidified melt.
 5. A melt launder according to claim 1, wherein the groove is 5-25 mm deep and essentially 5-25 mm wide.
 6. A melt launder according to claim 1 wherein the distance between the grooves is 5-25 mm.
 7. A melt launder according to claim 1, wherein the groove is located at a distance of at least 30 mm from lowest cooling channel.
 8. A melt launder according to claim 1, wherein the melt launder is manufactured by bending of one single element.
 9. A melt launder according to claim 1, wherein the melt launder is manufactured of two straight plates and worked into V-shape.
 10. A melt launder according to claim 1, wherein the bottom and edges of the melt launder are separate parts. 